In this study, a two‐stage system comprising a heat pump evaporator integrating heating and dehumidification was designed. Evaporator 1 pre‐dehumidified the air and evaporator 2 recovered the heat from the remaining air treated by evaporator 1. The low‐humidity air condensed by the two‐stage evaporator could be used for drying materials directly. The evaporator could obtain different heating and drying conditions by adjusting the air velocity of evaporator 2. This study established a model for heat and mass transfer involving a two‐stage evaporator under wet conditions. The evaporator's heat and mass transfer attributes were simulated, and the simulation results were found to be in high conformity with the experimental values. The relative error of temperature was ‐3.0‐3.0%, and the relative error of humidity was ‐10.0‐3.0%. The liquid film was mainly distributed at the beginning of the fins and decreased along the length of the fins. The relative humidity of the air increased by 10.0%, the thickness of the liquid film increased by 65.0%, and the temperature of the liquid film increased by 1.5%. The air velocity increased by 1.0 m s^‐1, and the liquid film temperature decreased by 6.7%. The mass transfer coefficient increased with increasing air velocity, while it decreased with increasing air relative humidity. The air velocity did not affect the latent heat ratio (LHR) of the evaporators. Moreover, the LHR of evaporator 1 was less than that of evaporator 2. Increasing the air velocity of evaporator 2 could provide more heat for the refrigerant, whereas decreasing the air velocity of evaporator 2 could increase the dehumidification capacity of the evaporator to unit air of mass and provide low‐humidity air for the drying box.

中文翻译：

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加热除湿一体式热泵两级蒸发器的性能及液膜分布研究

在本研究中，设计了一个包括热泵蒸发器的两级系统，该蒸发器集成了加热和除湿功能。蒸发器1对空气进行预除湿，而蒸发器2从蒸发器1处理过的剩余空气中回收热量。由两级蒸发器冷凝的低湿空气可直接用于干燥物料。通过调节蒸发器2的空气速度，蒸发器可以获得不同的加热和干燥条件。这项研究建立了一个在湿润条件下涉及两级蒸发器的传热传质模型。对蒸发器的传热和传质特性进行了仿真，仿真结果与实验值高度吻合。温度的相对误差为-3.0-3.0％，湿度的相对误差为-10.0-3.0％。液膜主要分布在鳍片的开始处，并沿着鳍片的长度减小。空气的相对湿度增加了10.0％，液膜的厚度增加了65.0％，液膜的温度增加了1.5％。空气速度增加1.0毫秒^‐1，液膜温度下降6.7％。传质系数随着空气速度的增加而增加，而随着空气相对湿度的增加而减小。空气速度不影响蒸发器的潜热比（LHR）。此外，蒸发器1的LHR小于蒸发器2的LHR。增加蒸发器2的风速可以为制冷剂提供更多的热量，而降低蒸发器2的风速可以提高蒸发器对单位空气的除湿能力。并为干燥箱提供低湿度的空气。